The present invention relates to transmission mechanisms for bicycles and relates more particularly to a multipurpose transmission mechanism for a bicycle which can be controlled to propel a bicycle or the like by foot pedals through crank or lever transmission or, alternatively through crank and lever transmission.
In regular bicycles, tricycles or stationary bicycles, power transmission is generally made through rotary type of crank motion or reciprocating type of lever motion (as disclosed in U.S. Pat. No. 4,575,649). In crank-driven type of power transmission mechanism, it requires much labor to drive the crank to pass through the dead angle (when the pedal of the crank is to be rotated from an upper limit position toward a lower limit position). Further, driving foot pedals to carry cranks to alternatively perform circular motion is quite monotonous and uninteresting. In lever motion type of power transmission mechanism, there is no dead angle within the cycle of lever motion and, the stroke of the pedals can be freely adjusted. Although it is adjustable, loss of inertia force at the upper as well as the lower changing point is inevitable.